Process for making inactive menthol



Patented Sept. 23, 1930 UNITED STATES.

PATENT OFFICE- KARL SGHbLLKOPF, OF DUSSELDORF-OBERKASSEL, AND ARTHUR SERINI, OF DUSSEL- DORF-HEERDT, GERMANY, ASSIGNORS T0 RHEINISGHE KAMPFER-FABRIK GESELL- SGEAFT MIT BESOHRANKTER I-IAFIUNG, OF DUSSELDORF-OBERKASSEL, GERMANY PROCESS FOR MAKING INACTIVE MENTHOL No Drawing. Original application filed June 30,1927, Serial No. 202,739, and in Germany February 15, 1927. Divided and this application filed September 20, 1928. Serial No. 307,334.

centigrade, the inactive neo-isomenthol being employed by itself or in admixture with other isomers of inactive menthol and separating the crude inactive menthol from the resulting mixture by physical methods, for instance, by freezing-out or fractional distillation, purifying the crude inactive menthol by conversion into its esters as described in U. S. Patent 1,672,346 and transforming the residual isomers anew.

Example 1.Three parts of metallic sodium are dissolved in 100 parts of inactive neo-isomenthol, and the mixture of neoisomenthol and sodium neo-is0mentholate is heated at 180 degrees centigrade for about 24 hours. The reaction product is then driven ofi by means of steam. The inactive menthol is separated from the resulting mix ture of isomers by freezing out or fractional distillation, and is further purified by way of the esters. The isomeric menthols left from the separation and purification are subjected to further transformation.

E mample %.A mixture of parts of inactive neo-isomenthol and 50 parts of a mix ture of liquid isomeric menthols left over from Example 1, is treated with the corresponding sodium mentholates as in Example 1, and the resulting menthols mixture is subjected to further treatment as described therein.

We claim! 1 1. The process for manufacturing inactive menthol, the racemate of natural menthol, which consists in heating inactive neoisomenthol with mentholates of the alkali forming metals and separating from the reaction product crude inactive menthol by physical methods.

2. The process for manufacturing inactive menthol, the racemate of naturalmenthol, which consists in heating inactive neoisomenthol admixed with other isomers of inactive menthol, with mentholates of the alkali forming metals and separating from the reaction product crude inactive menthol by physical methods. V

3. The process for manufacturing inactive menthol, the racemate of natural menthol, which consists in heating. inactive neoisomenthol with mentholates of the alkali forming metals and separating from the reactlon product crude inactive menthol by fractional distillation.

4:. The process for manufacturing inactive menthol, the racemate of natural menthol, which consists in heating inactive neolsomenthol mixed with other isomers of inactlve menthol with mentholates of the alkali forming metals, and separating from the reactionproduct crude inactive menthol by fractional distillation. r

5. The process for manufacturing inac tive menthol, the racemate of natural menthol,which consists in heating inactive neoisomenthol with mentholates of the alkali forming metals and separating from the reaction product crude inactive menthol by fractional crystallization.

6. The process for manufacturing inactive menthol, the racemate of natural menthol, which consists in heating inactive neoisomenthol mixed with other isomers of inactivejmenthol with mentholates of the alkali forming metals, and separating from the reaction product crude inactive menthol by fractional crystallization. In testimony. whereof we afiix our signa tures.

.KARL SCHOLLKOPR.

ARTHUR SERINI. 

